Motor unit irritability in Beagles Before and after exposure to cholinesterase inhibitors.

Electromyographic (EMG) examinations were performed on Beagles before and for 7 days after oral administration of one of the following organophosphate (OP) compounds; ronnel (55.0 or 110.0 mg/kg), dichlorvos (29.7, 59.4, or 148.5 mg/kg), or cythioate (24.8 or 33.0 mg/kg). The EMG values determined were evoked potentials, after-discharge activity, F-wave activity, nerve conduction velocity, and motor unit potential activity associated with interosseous and pectineal reflexes. Erythrocyte cholinesterase (ChE) activities were measured in some dogs. Ronnel did not have an effect on ChE activity, whereas dichlorvos and cythioate, at all dosage levels, had an inhibitory effect. Some dogs had minor signs of OP toxicosis. The EMG changes for individual OP compounds were not statistically significant (P greater than 0.05), but pooled results revealed an increased duration of evoked potentials, increased after-discharge activity, and decreased F-wave activity; however, only the effect on duration was significant (P less than 0.05). Reflex motor unit potential activity and nerve conduction velocities were not affected. Effects of neostigmine (0.1 to 0.4 mg/kg) given IV to anesthetized, atropinized Beagles were similar to those effects shown by pooled data for the OP compounds, but considerably more muscle fasciculation was produced. Results of this study indicate that even when erythrocyte ChE activity is reduced by OP compounds at dosage levels that produce no or minimal visible signs of toxicosis, EMG reveals little evidence for increased motor unit irritability.     

Motor nerve conduction parameters in the cat

The electrophysiological characteristics of motor conduction in normal cats have been determined using an alligator clip as a surface electrode to record the compound muscle action potential (CMAP) following stimulation of the tibial, ulnar and fibular nerves. Data on nerve conduction velocity, residual latency and the amplitude and area of the CMAP have been determined using a computerised electromyography unit. Motor nerve conduction was substantially faster in cats than dogs and the site of stimulation had less effect on the size and area of the CMAP. Although a small decline in the amplitude of successive CMAPs was observed following repetitive stimulation of the tibial and ulnar nerve at 20 Hz, the decrement was less marked than in the dog.     

Electrodiagnostic evaluation of peripheral nerve function in rheas and barred owls

OBJECTIVE: To establish reference values for electrodiagnostic evaluation of peripheral nerve function in birds. ANIMALS: 6 rheas and 6 barred owls. PROCEDURE: Birds were anesthetized with propofol or isoflurane in oxygen. Using a computer-based electromyograph system and needle electrodes for stimulation and recording, electromyography (EMG) was performed on the pectoral, biceps brachialis, and gastrocnemius muscles, and evoked EMG was performed on the tibial and ulnar nerves. Motor nerve conduction velocity (MNCV) was calculated. Repetitive stimulation was performed on these 2 nerves. Late F waves were recorded for each nerve, when possible. RESULTS: Activity was evident during insertion of the electrodes, but muscles tested were electrically quiescent after spontaneous EMG. Motor nerve conduction velocity was faster in the tibial nerve than ulnar nerve but did not differ significantly between species. Mean +/- SEM MNCV was 132.3+/-7.8 m/s for the tibial nerve and 59.7+/-7.8 m/s for the ulnar nerve. A significant difference was not observed in responses at the fourth or ninth stimulation during repetitive stimulation. Subsequent to the initial stimulation, amplitudes were +/-22.7% of the initial motor potential amplitude. Recorded F waves were inconsistent, which may have been associated with technique. CONCLUSIONS AND CLINICAL RELEVANCE: Reference range (mean +/-2 SEM) for MNCV was 34.1 to 75.3 m/s for the ulnar nerve and 116.7 to 147.9 m/s for the tibial nerve in barred owls and rheas. After repetitive stimulation, motor potential amplitudes may be +/-22.7% of the initial amplitude response.     

F-wave conduction velocity, persistence, and amplitude for the tibial nerve in clinically normal cats

OBJECTIVE: To establish a method of F-wave evaluation and to determine normative values of F-wave parameters, including F-wave conduction velocity, persistence, and amplitude for the tibial nerve in cats. ANIMALS: 30 clinically normal cats. PROCEDURES: F-waves elicited in the interosseous muscles by stimulation of the tibial nerve were recorded, and linear regression analyses of the shortest latency versus the length of the tibial nerve and the limb length were performed. F-wave persistence was calculated by dividing the number of recorded F-waves by the number of stimuli. RESULTS: The correlation coefficient between F-wave latency and nerve length was 0.92, and that between F-wave latency and limb length was 0.58. Mean +/- SD F-wave conduction velocity of the tibial nerve was calculated to be 97.1 +/- 5.0 m/s. Linear regression analysis yielded the regression equation as follows: F-wave latency (milliseconds) = 2.60 + (0.02 x nerve length [mm]). Mean F-wave persistence and amplitude were 98.7 +/- 2.3% and 1.01 +/- 0.62 mV, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that nerve length should be used for nerve conduction studies of F-waves in felids. The regression equation for F-wave latency, conduction velocity, persistence, and amplitude may contribute to the diagnosis of nervous system diseases or injury in cats, such as trauma to the spinal cord or diabetic neuropathy.     

Electrophysiologic Assessment of Acute Polyradiculoneuropathy in Dogs: Comparison with Guillain-Barré Syndrome in People

Electrophysiologic investigations of motor and sensory nerve as well as ventral nerve root function were performed on 12 dogs with suspected acute canine polyradiculoneuropathy (ACP) at different stages and with different severity of disease. The most reliable electrophysiologic indicators of ACP were electromyographic changes (occurring in 100% of affected dogs), significantly decreased compound muscle action potential amplitudes (in 75, 90, and 100% of affected dogs at all sites along the sciatic/tibial, radial, and ulnar nerves, respectively), increased minimum F-wave latencies (67%), increased F ratios (92%), and decreased F-wave amplitudes (67%). These findings suggest that ACP represents a peripheral motor axonopathy, with demyelination and axonal involvement also occurring in ventral nerve roots. Evidence of peripheral demyelination was present in some dogs although it was overshadowed by the prominent axonopathy. ACP more closely resembles the acute axonal or intermediate forms of Guillain-Barré syndrome in people.     

Progressive axonopathy: an inherited neuropathy of Boxer dogs. 1. Further studies of the clinical and electrophysiological features

The clinical and electrophysiological findings in 14 Boxer dogs with progressive axonopathy (PA) are described. The salient clinical features are hind-limb ataxia which may later involve forelegs, proprioceptive defects, hypotonia, patellar areflexia, absence of muscle atrophy and, in a few instances, ocular tremor and head bobbing. The outward signs are often observed by 2–3 months of age but clinical testing can reveal patellar areflexia at 1 month of age. After an initial progression, the signs may stabilize and dogs are alive at 4 years of age having shown no deterioration over the previous 2 years. The electrophysiology shows reduced motor nerve conduction velocities and evoked potential amplitudes after about 4 months of age. The F-wave latency is considerably increased. Sensory nerves also show a marked reduction in the amplitude of their evoked potentials and eventually cease to conduct. Abnormal spontaneous activity is not a feature on electromyography. The conduction defects probably reflect to some degree the reduced nerve fibre diameters and myelin sheath changes found in PA although other factors may also be operating. The study shows that PA can be diagnosed with reasonable confidence by routine clinical testing at an early age.     

A new method for recording and analysing evoked motor potentials from dogs

Normal values for motor conduction in the tibial, ulnar and fibular nerves of dogs have been determined using a new method for recording and analysing evoked motor potentials. The use of an alligator clip as a roving surface electrode for recording, and a personal computer to analyse the evoked potentials has facilitated faster and more reproducible motor conduction studies. Compound muscle action potential (CMAP) and motor nerve conduction velocity data are in good agreement with previous studies. Normal values for CMAP area, residual latency and proximal to distal ratios for CMAP area and amplitude are presented for the first time.     

F-wave latency and F-wave conduction velocity for the tibial nerve in clinically normal dogs

OBJECTIVE: To establish a method of F-wave examinations and to determine values of F-wave conduction velocity (FWCV) and F-wave latency for the tibial nerve of clinically normal dogs. ANIMALS: 21 clinically normal dogs. PROCEDURE: The F-waves were elicited from the interosseous muscles via stimulation of the tibial nerve. The FWCV was determined by using the F-wave shortest value and the surface distance corresponding to the tibial nerve length. Correlation between the smallest latency value of the F-wave and the length of the tibial nerve and between the FWCV and rectal temperature were closely examined. RESULTS: F-wave latency was proportional to the length of the tibial nerve (correlation coefficient, 0.929). Mean +/- SD FWCV was 77.98 +/- 8.62 m/s. Regression equation was as follows: F-wave latency = 2.799 + (0.029 X length of the tibial nerve).The FWCV was increased when the measured rectal temperature was high. Correlation coefficient between FWCV and rectal temperature was 0.665. CONCLUSIONS AND CLINICAL RELEVANCE: In the study reported here, we established a reliable method for clinical evaluation of the F-wave. When assessing nerve conduction velocity, it is essential to measure nerve length along the pathway that the nerve impulse travels. This method of F-wave examination is a useful diagnostic tool for the evaluation of suspected dysfunction of the peripheral nervous system.     

Electrophysiological evidence of peripheral nerve dysfunction in six dogs with botulism type C

In six dogs with botulism type C electrophysiological examinations showed: fibrillation potentials and prolonged insertional activity; low amplitude of the evoked muscle action potential; decrease in amplitude of the compound muscle action potential with slow repetitive stimulation; slowing of motor and sensory velocities in the peripheral nerve; and restoration of velocity and amplitude corresponding to clinical improvement. These findings indicate peripheral nerve dysfunction which cannot be explained adequately by current knowledge of the action of botulinum toxin on cholinergic nerve endings. It is therefore suggested that botulinum toxin also interferes with peripheral nerve conduction.     

Preservation of striated-muscle urethral sphincter function with use of a surgical technique for perineal urethrostomy in cats

It has been reported that perineal urethrostomy resulted in impairment of striated-muscle urethral sphincter function in male cats, as measured by urethral pressure profilometry and electromyography (EMG). Our study was undertaken to describe and evaluate a surgical technique for perineal urethrostomy that reduces trauma to the urethral branches of the pudendal nerve. Perineal urethrostomy was performed on 10 healthy neutered cats after demonstrating that they had normal urethral sphincter function by urethral pressure profilometry (maximal urethral closure pressure [MUCP] = 151 +/- 52 cm of water) and EMG activity at the level of the striated-muscle sphincter before surgery. All cats had normal urethral sphincter function 1 week (MUCP = 194 +/- 19 cm of water, EMG activity present) and 3 weeks (MUCP greater than 200 cm of water, EMG activity present) after surgery. These results indicated that preservation of the urethral branches of the pudendal nerve during urethrostomy preserved striated-muscle urethral sphincter function.     

Toxicity and outcome in cats with oral squamous cell carcinoma after accelerated hypofractionated radiotherapy and concurrent systemic treatment

Recently, a multimodal approach to oral squamous cell carcinoma (SCC) in cats, combining medical treatment and accelerated radiation therapy, showed a substantial outcome improvement in a small pilot study. Herein we retrospectively review 51 cats with unresectable, histologically confirmed oral SCC and a complete initial staging work‐up: cats in group A (n = 24) received medical anti‐angiogenic treatment consisting of bleomycin, piroxicam and thalidomide, cats in group B (n = 27) received the anti‐angiogenic treatment and concurrent accelerated hypofractionated radiation therapy with 48Gy delivered in 10 fractions. Overall median progression‐free interval (PFI) was poor with 70 days (95% CI: 48;93). In the irradiated cats (group B), however, PFI was significantly longer with 179 days (95% CI: 58;301) days, vs 30 days (95% CI: 23;38) in medically only treated cats (P < .001). Overall median overall survival (OS) was 89 days (95% CI: 55;124), again significantly longer in the irradiated cats (group B) with 136 (95% CI: 40;233) vs 38 days (95% CI: 23;54) (P < .001). In 8 of the 27 (29.6%) cats in group B, however, severe toxicity (grade 3) occurred. Neither onset nor severity of toxicity could be associated with any of the tested variables, including anatomic site, tumour size, clinical stage and duration of neoadjuvant medical treatment. Given the potential severe acute effects and the impact on quality of life after chemo‐radiotherapy, owners must be clearly informed about the risks of treatment. With the overall poor outcome and high occurrence of acute toxicity, we cannot recommend the use of this accelerated radiation protocol combined with anti‐angiogenic therapy for oral SCC in cats.     

The role of quantitative electromyography (EMG) in horses suspected of acute and chronic grass sickness

REASONS FOR PERFORMING THE STUDY: Clinical evidence of motor neuron involvement in equine grass sickness (EGS) has not been reported. HYPOTHESIS: Quantitative electromyography (EMG) analysis can elucidate subtle changes of the lower motor neuron system present in horses with EGS, performed ante mortem. METHODS: Fourteen horses diagnosed clinically with acute, subacute or chronic EGS were examined and quantitative EMG performed. Previously published data on healthy horses and horses with proven lower motor neuron disease (LMND) were used as controls. In 8 horses post mortem examination was performed, and in 7 muscle biopsies of the lateral vastus muscle underwent histopathology and morphometry. RESULTS: Clinical electrophysiological evidence of neuropathy was present in 12 horses. Analysis of data from the first 4 horses resulted in 95% confidence intervals (CI) of nontransformed data for motor unit action potential (MUP) duration in subclavian, triceps and lateral vastus muscle of 11.0-13.7, 14.8-20.3 and 12.2-17.2 msecs, respectively, and for MUP amplitude 291-453, 1026-1892 and 957-1736 microV, respectively. For number of phases the 95% CI was 3.6-4.4, 2.9-3.6 and 2.9-3.4, respectively, and for number of turns 5.0-6.5, 4.3-5.3 and 3.7-4.6, respectively. No changes in duration of insertional activity were measured. Pathological spontaneous activity was observed in all horses. EGS as evidenced by degenerative changes in the autonomic ganglia in combination with minor degenerative changes of the spinal lower motor neurons was observed on post mortem examination in all 8 available autopsies. In muscle biopsies of 4 out of 7 horses changes consistent with slight neurogenic atrophy were found. CONCLUSIONS AND POTENTIAL RELEVANCE: EMG results demonstrated the presence of a neuropathy of skeletal muscles in all horses suspected to have EGS. The combination of clinical and electrophysiological evidence may aid differential diagnosis of neurogenic disease in cases of weight loss and colic.     

Retrospective Study of Streptokinase Administration in 46 Cats with Arterial Thromboembolism

A retrospective evaluation was performed on 46 cats with arterial thromboembolism (ATE) that were treated with streptokinase (SK). Significant heart disease was diagnosed in 45/46 cats, and 21/46 cats had congestive heart failure. Variable dosing schemes of streptokinase were administered within 1–20 hours following the onset of clinical signs (median = 5.5 hours). There was no difference between survivors (S) and non-survivors (NS), based on time of administration of SK after onset of clinical signs. Twenty-five (54%) of the cats had return of pulses within 2–24 hours of treatment. Fourteen (30%) of the cats had return of motor function between 9 hours and 6 days. Fifteen of the cats (33%) were discharged from the hospital, 18 (39%) died in the hospital, and 13 (28%) cats were euthanized due to complications or poor response to treatment. Four of 5 cats (80%) with single limb dysfunction survived to hospital discharge. Life threatening hyperkalemia was diagnosed in 16 cats (35%) after SK administration. Hyperkalemia was more likely to occur with the longer duration of SK infusion. Eleven cats (24%) developed clinical signs of bleeding following SK administration and 3 of these cats required a blood transfusion. Laboratory testing documented coagulopathy following SK administration in 11 out of 17 cats tested. Hypothermia and azotemia prior to SK administration and the development of hyperkalemia were negatively associated with survival.     

Outcome following surgical removal of nonvisceral soft tissue sarcomas in cats: 42 cases (1992-2000)

OBJECTIVE: To identify factors associated with outcome of cats with nonvisceral soft tissue sarcomas treated with surgery alone. DESIGN: Retrospective study. ANIMALS: 42 cats. PROCEDURE: Medical records were reviewed for clinically relevant data, and histologic samples were examined. Follow-up information was obtained by means of physical examination or through telephone conversations with referring veterinarians and owners. The Kaplan-Meier method was used to construct survival curves. RESULTS: Median survival time was 608 days (range, 85 to 2,291 days), although 24 cats were still alive at the time of the study. Tumor size (ie, diameter) and histologic type were significantly associated with survival time. Median survival time was significantly longer in cats with tumors that were < 2 cm in diameter, compared with cats in which tumors were > 2 cm. Median survival times for cats with a fibrosarcoma or nerve sheath tumor were significantly longer than median time for cats with a malignant fibrous histiocytoma. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that tumor size and type are significantly associated with survival time in cats with nonvisceral soft tissue tumors.     

Combined paravertebral plexus block and parasacral sciatic block in healthy dogs

ObjectiveTo evaluate the effectiveness of paravertebral lumbar plexus block combined with parasacral sciatic block to anesthetize one hind limb in awake dogs.Study designRandomized, controlled, blinded experimental study.AnimalsEight healthy mongrel dogs weighing 12.4 ± 4.5 kg and aged 7 ± 2.33 years.MethodsAfter sedation with medetomidine, dogs received B1: bupivacaine 0.25%, 0.2 mL kg^?1, B2: bupivacaine 0.5%, 0.2 mL kg^?1, B3: bupivacaine 0.25% 0.4 mL kg^?1, P1: NaCl 0.2 mL kg^?1, P2: NaCl 0.4 mL kg^?1. The lumbosacral plexus was blocked through a paravertebral block of the fourth, fifth and sixth lumbar nerves combined with a parasacral block. The relevant nerves were located using a nerve stimulator and injections of each treatment were administered. Degree and durations of sensory blockade were determined through the response to a Halsted clamp pressure on the skin innervated by the saphenous/femoral and lateral cutaneous femoral nerves (lumbar dermatomes) and by the peroneal and tibial nerves. The degree and duration of motor blockade was assessed evaluating the ability to walk normally and proprioception.ResultsP1 and P2 treatments did not show any grade of sensory or motor blockade. The B2 treatment produced a higher degree of sensory blockade compared to B1 and B3 for both lumbar and sciatic dermatomes. There was no significant difference in the degree of sensory blockade comparing B1 to B3. The B2 treatment had greater motor blockade compared to B1 and B3. The duration of sensory and motor blockade was longer in B2 compared to B1 and B3.Conclusion and clinical relevanceWhen the nerve stimulator is used to perform the lumbosacral plexus block, the concentration of the bupivacaine has a more important role than the volume to produce a more solid and longer block.     

Electrodiagnostic evaluation in feline hypertrophic muscular dystrophy

Standard needle electromyography (EMG) of 56 muscles and nerve conduction velocities (NCV) of the ulnar and common peroneal nerves were investigated in each of six cats affected with hypertrophic feline muscular dystrophy, 10 related heterozygote carriers and 10 normal cats. The EMG findings were considered normal in carrier and control cats, and consisted of 33% normal readings, 22% myotonic discharges, 18% fibrillation potentials, 11% prolonged insertional potentials, 10% complex repetitive discharges and 6% positive sharp waves in affected cats. Muscles of the proximal limbs were most frequently affected. No differences in NCV were found between the three cat groups. It was concluded that dystrophin-deficient dystrophic cats have widespread and frequent EMG changes, predominantly myotonic discharges and fibrillation potentials, which are most pronounced in the proximal appendicular muscles.     

A retrospective study of (90)Strontium plesiotherapy for feline squamous cell carcinoma of the nasal planum

The responses of 15 cats with histologically (n=14) or cytologically (n=1) confirmed nasal squamous cell carcinoma treated with (90)Strontium plesiotherapy were reviewed retrospectively. Cats were treated such that a total dose of 50Gy was delivered at a depth of 2mm, administered in five fractions over a 10-day period. Of the cats, 11 were stage T(2), three were T(is) and one had only a cytological diagnosis precluding staging. Eleven of the cats achieved complete response (no visible lesion after 6-8 weeks) following the first cycle of therapy, and two cats with partial response achieved complete response with a second cycle of therapy. The remaining two cats achieved partial response following therapy, but further intervention was declined. Euthanasia was performed in these two cats because of progressive disease after 81 and 142 days. Of the 85% of cats that achieved a complete response, there was no recurrence of disease during a follow-up period of 134-2,043 days (median 652 days). In addition to prolonged disease-free survivals, (90)Strontium therapy produced excellent cosmetic results from the owners' perspective. These results demonstrate that superficial squamous cell carcinoma of the feline nasal planum responds excellently to (90)Strontium plesiotherapy, and this form of therapy may offer advantages over other alternatives currently available.     

Tetanus in cats: 3 case descriptions

Three cats with spasticity on one leg or on all four limbs were presented between 1996 and 1998 at the Department of clinical veterinary medicine, Section of neurology, Vetsuisse-Faculty of Bern. The presumptive diagnosis was tetanus. A focal form was present in two cases and generalised tetanus in one cat. All cats had a history of injury at the affected legs respectively at the neck. The first clinical signs were seen between two days and three weeks after injury. The bacteriologic examination of serous fluid from the site of injury revealed an infection with Clostridium. EMG in one cat during anaesthesia showed motor united potentials (MUPs) on the spastic leg. All patients received antibiotics (Penicillin, respectively Amoxicillin/Clavulanic acid and Metronidazol). Supportive aid were initially sedation, wound revision and in one cat nutrition through oesophageal sonde. In a second phase physiotherapy was performed. All three animals were significantly better after a couple of weeks, two cats were without symptoms after eight and five weeks respectively.